Field of the Invention
The present invention relates to a toner for developing an electrostatic latent image and a producing method therefor.
Description of the Related Art
In an electrophotographic image forming method, for example, a two-component developer (toner), which contains a toner particle containing a colorant and a carrier particle for stirring and conveying the toner particle, is used. In the image forming method, for the purpose of increasing the speed of image formation, reducing a load to the environment, or the like, there is a demand for decreasing heat energy in fixing. For this reason, the toner particle needs to have low-temperature fixability. In this regard, it is generally known to blend a crystalline resin, such as crystalline polyester, having an excellent sharp melting property with a binder resin.
For example, in a binder resin containing a crystalline polyester resin and an amorphous resin, when a temperature of the binder resin exceeds a melting point of the crystalline polyester due to, for example, heating in fixing, the crystalline part of the crystalline polyester resin in the binder resin is melted. As a result, the crystalline polyester resin and the amorphous resin are compatible each other, and thus the low-temperature fixation of the toner particle is realized. However, in the toner particle, compatibilization of both the resins is caused at a reaction temperature in producing of the toner particle, and thus the toner particle becomes soft. As a result, the storage stability of the toner may not be sufficient.
As a countermeasure for suppressing the compatibilization in producing of the toner particle described above, a binder resin containing a resin into which a crystal nucleating agent having a melting point higher than a melting point of a binder resin is introduced, is known. In the binder resin, for example, there is known a resin in which a crystalline polyester resin, an amorphous polyester resin, and a vinyl-based resin component are bonded to a polyolefin resin component, the resin having a crystal nucleating agent part at the terminal of the crystalline polyester resin. The crystal nucleating agent part is a part derived from at least one compound selected from the group consisting of aliphatic carboxylic acid having 10 to 30 carbon atoms and aliphatic alcohol having 10 to 30 carbon atoms (for example, see JP 2014-26273 A).
Further, in the binder resin, for example, there is known a resin containing a crystalline polyester resin and an amorphous polyester resin, the resin having the crystal nucleating agent part at the terminal of the crystalline polyester resin (for example, see JP 2014-26274 A and JP 2014-26276 A).
In the aforementioned binder resin of the related art, the crystallization of the crystalline resin component in the binder resin is promoted by introduction of a crystal nucleating agent. However, in the binder resin, the introduced crystal nucleating agent is difficult to uniformly disperse in the inside of a toner parent particle, and thus may be eccentrically located on the surface of the toner parent particle or in the vicinity thereof. For this reason, the binder resin may be melted on the surface of the toner parent particle or in the vicinity thereof due to heat from the outside at the time of production or storage. As a result, the storage stability of the toner may not be sufficient. In addition, since some components in the binder resin are eccentrically located on the surface of the toner parent particle or in the vicinity thereof, the charging uniformity of the toner particle may not be sufficient.